This invention relates to an electroless process for coating a non-conductive substrate with a silylated polyamine-noble metal (SPNM) complex and then optionally plating the coated substrate with a metal from a metal salt solution.
Electroless plating processes for the application of a conductive metal onto the surface of a non-catalytic substrate are known. By "electroless plating process", we mean plating processes which do not use electric current. An example is a chemical plating process in which a non-conductive substrate is plated from an aqueous solution having dissolved therein a metal salt corresponding to the metal to be deposited upon such substrate. One such process, described in U.S. Pat. No. 3,338,726 to Berzins, involves first applying a coating of stannous chloride to the substrate to sensitize it. The substrate so sensitized is then coated with a thin film of palladium chloride which will serve as a catalyst to promote the reduction of metal from an aqueous solution.
We have found that an effective electroless metal plating process can be carried out by a two stage process. The first stage involves applying a thin coating of an SPNM complex to a non-conductive substrate and the second stage is bringing the coated substrate into contact with a solution containing a metal salt whereby metal from the metal salt is deposited onto the surface of the substrate.